The present invention relates to a polishing apparatus and method for polishing a surface of a work-piece such as a semiconductor wafer to a high degree of fineness.
In a semiconductor device manufacturing process, a polishing apparatus is used to polish surfaces of semiconductor wafers. However, during polishing particles become detached from the wafer and scattered around the polishing apparatus, and hence it has not been possible to use a conventional polishing apparatus in a clean room environment. In addition, in the conventional system, following polishing, the wafer is placed in a mobile water tank for transportation to a cleaning apparatus, which is inefficient in terms of both the time and space required to complete a polishing and cleaning operation.
To solve the above-mentioned problems, a so-called dry-in/dry-out system has been developed in which polishing and cleaning processes are carried out in an apparatus enclosed within a housing. In the dry-in/dry-out system, a semiconductor wafer is loaded into the apparatus in a dry state and, following polishing and cleaning, is unloaded in a dry state.
Aside from the development of the dry in/dry out system, a polishing apparatus per se has been modified such that it is able to be used in a clean room. Further, improvements in the processing efficiencies of a polishing apparatus and a cleaning apparatus have enabled their installation in a space equal to or smaller than that required for the installation of a dry-in/dry-out system. However, there remains a difficulty in the automation of the wafer transportation means incorporating a mobile water tank.
An object of the present invention is to provide a polishing apparatus which is applicable to the above-described dry-in/dry-out polishing system whereby the efficiency with which work-pieces are polished, such as semiconductor wafers, can be increased both in terms of the time required and space utilized.
In accordance with the present invention, there is provided a polishing apparatus comprising a polishing unit including a turntable provided on one side surface with a polishing surface and first and second substrate carriers each adapted to hold a substrate and to bring the substrate into contact with the polishing surface. Each of the first and second substrate carriers is movable between a first position where the substrate carrier receives a substrate and a second position where the substrate carrier is positioned over the polishing surface and is able to bring the substrate into contact with the polishing surface of the turntable. The first substrate carrier is movable between its first and second positions stated above while the second substrate carrier is positioned at its second position and vice versa.
The polishing apparatus may include first and second pivotal arms which support the first and second substrate carriers, respectively, to enable the first and second substrate carriers to move between their first and second positions stated above.
The second position stated above may include a polishing position where the substrate held by the substrate carrier is kept in contact with the polishing surface of the turntable and a waiting position where the substrate held by the substrate carrier is spaced away from the polishing surface.
The stated polishing unit may comprise a substrate transfer device for receiving substrates to be polished from the outside and positioning the substrates to enable the first and second substrate carriers to respectively pick up and hold the substrates. The wafer transfer device may be adapted to receive substrates which have been polished from the first and second substrate carriers positioned at their first positions.
The polishing unit may comprise first and second wafer transfer devices for receiving substrates to be polished from the outside and positioning the substrates to enable the first and second substrate carriers to pick up and hold the substrates, respectively. The wafer transfer devices may be adapted to receive substrates which have been polished from the first and second substrate carriers positioned at their first positions stated above.
In accordance with another aspect of the present invention, there is provided a polishing apparatus comprising a polishing unit including a turntable provided on one side surface with a polishing surface, and two substrate carriers each including a pivotal shaft, an arm having a center portion supported by the pivotal arm and opposite ends, and first and second substrate carriers provided on the opposite ends of the arm which are adapted to hold substrates, respectively. Each of the arms of the substrate carrier are pivotable about the pivotal shafts in such a manner that, in a first pivotal position, one of the first and second substrate carriers receives a substrate to be polished, while the other of the first and second substrate carriers is positioned over the polishing surface to enable the other substrate carrier to bring the substrate held thereby into contact with the polishing surface of the turntable, and in a second pivotal position, the other substrate carrier stated above receives a substrate to be polished, while the one substrate carrier stated above is positioned over the polishing surface to enable the one substrate carrier to bring the substrate held thereby into contact with the polishing surface of the turntable. The arms are movable between their first and second positions stated above without contacting each other.
The polishing unit may include a substrate transfer device for receiving substrates to be polished from the outside and positioning the substrates to enable the first and second substrate carriers to pick up and hold the substrates. The wafer transfer device may be adapted to receive substrates which have been polished from the first and second substrate carriers. The polishing unit may comprise two substrate transfer devices for respectively receiving substrates to be polished from the outside and positioning the substrates to enable the first and second substrate carriers to pick up and hold the substrates, respectively. The wafer transfer devices may be adapted to receive substrates which have been polished from the first and second substrate carriers.
According to a further aspect of the present invention, there is provided a polishing method comprising the steps of providing a turntable provided on its one side surface with a polishing surface, providing first and second substrate carriers each adapted to hold a substrate and to bring the substrate into contact with the polishing surface, turning the turntable, holding a substrate with the first substrate carrier, moving the first substrate carrier to bring the substrate held thereby into contact with the polishing surface to subject the substrate to polishing, and holding a substrate and then positioning the substrate over the polishing surface with the second substrate carrier, while the first substrate carrier keeps the substrate held thereby in contact with the polishing surface. Following completion of the polishing of the substrate held by the first substrate carrier, the substrate held by the second substrate carrier can be brought into contact with the polishing surface to subject the substrate to polishing without delay.
In accordance with the other aspect of the present invention, there is provided a polishing method comprising the steps of providing a turntable provided on its one side surface with a polishing surface, providing first and second substrate carriers each adapted to hold a substrate and to bring the substrate into contact with said polishing surface, turning the turntable, holding substrates by the first substrate carrier, moving the first substrate carrier to bring the substrate held thereby into contact with the polishing surface to subject the substrate to polishing, holding a substrate by the second substrate carrier and then bringing the substrate held by the second substrate carrier into contact with the polishing surface, while the first substrate carrier keeps the substrate held thereby in contact with the polishing surface, and moving the first substrate carrier to separate the substrate held thereby from the polishing surface following completion of polishing thereof, then exchanging the polished substrate with another substrate and bringing it into contact with the polishing surface, while the second substrate carrier keeps the substrate held thereby in contact with the polishing surface.
The above and other features and advantages of the present invention will become apparent from the following description and the appended claims taken in conjunction with the accompanying drawings.